(1) Field of the Invention
The present invention pertains to a manually operated liquid foaming dispenser. Specifically, the invention pertains to a manually operated trigger sprayer that is attached to the top of a bottle of liquid and has a manually manipulated trigger that is reciprocated to dispense the liquid from the container as a foam. The trigger sprayer includes a liquid pump chamber and an air pump chamber that respectively pump liquid and air under pressure to a discharge passage of the sprayer where the liquid and air are mixed, generating the foam dispensed from the sprayer.
(2) Field of the Invention
Manually operated liquid dispensers that dispense liquid as a foam are known in the prior art. Common among these types of dispensers are manually operated trigger sprayers that pump liquid from a bottle container attached to the trigger sprayer and dispense the liquid as a foam that is discharged from the trigger sprayer. The dispensing nozzle of this type of trigger sprayer typically discharges the liquid as a spray toward an obstruction that is vented to the atmosphere. The spray hitting the obstruction mixes the liquid spray with the air of the atmosphere producing the foam that is discharged from the trigger sprayer.
The typical trigger sprayer that discharges a foam is constructed of a sprayer housing containing a pump chamber, a liquid supply passage, and a liquid discharge passage. The liquid supply passage communicates the pump chamber with the liquid contained in the container attached to the trigger sprayer. A pump piston is mounted in the pump chamber for reciprocating movement between charge and discharge positions. A trigger is attached to the sprayer housing and is connected to the pump piston for moving the pump piston. The pump chamber also communicates with the liquid discharge passage which extends from the pump chamber to the discharge nozzle of the trigger sprayer.
A first check valve assembly is positioned between the pump chamber and the liquid supply passage. The first check valve allows liquid to travel through a dip tube and the liquid supply passage into the pump chamber when the pump piston is moved to the charge position, and prevents the reverse flow of liquid from the pump chamber when the pump piston is moved to the discharge position. A second check valve is usually positioned in the discharge passage between the pump chamber and the discharge nozzle. The additional check valve assembly allows the flow of liquid from the pump chamber through the discharge passage to the discharge nozzle when the pump piston is moved to the discharge position, but prevents the reverse flow of liquid and/or air when the pump piston is moved to the charge position.
The basic construction of the foaming liquid trigger sprayer described above is well suited for dispensing liquids where the desired foaming of the liquid is marginal, for example in dispensing foaming liquid kitchen cleaners or bathroom cleaners. However, the foaming trigger sprayers cannot produce a more dense foam such as that of shaving cream.
To produce a more dense foam such as that of shaving cream from a liquid dispenser requires that both the liquid and air being mixed by the dispenser be under pressure. This requires that the manually operated foaming dispenser include both a liquid pump chamber and an air pump chamber. The addition of the air pump chamber to the manually operated dispenser increases the number of component parts of the dispenser. The air pump chamber must also have an air pump piston that moves between the charge and discharge positions in the air pump chamber to draw air into the chamber and force air under pressure from the chamber. In addition, the air pump chamber must also have a check valve assembly that allows the air of the exterior environment of the dispenser to flow into the air pump chamber when the air pump piston is moved to the charge position and prevents the flow of air from the air pump chamber to the exterior environment when the air pump piston is moved to the discharge position. A second check valve assembly is also needed to control the flow of pressurized air from the air pump chamber to the discharge passage when the air pump piston is moved to the discharge position, and to prevent the reverse flow of air from the discharge passage to the air pump chamber when the air pump piston is moved to the charge position. These additional component parts required by this type of liquid foaming dispenser significantly increase manufacturing costs.